Make server respond to "fetch" with output formatted for the client's OS family

src/backend/2globalsUNIX.go

@@ -10,5 +10,5 @@ var ConfigPath = ConfigDir + "/libmutton.ini"
 // PathSeparator defines the character used to separate directories in a path (platform-specific)
 const (
 	PathSeparator = "/"
-	Windows       = false // TODO temporary, remove after native sync is implemented
+	IsWindows     = false
 )

src/backend/2globalsWIN.go

@@ -10,5 +10,5 @@ var ConfigPath = ConfigDir + "\\libmutton.ini"
 // PathSeparator defines the character used to separate directories in a path (platform-specific)
 const (
 	PathSeparator = "\\"
-	Windows       = true // TODO temporary, remove after native sync is implemented
+	IsWindows     = true
 )